The committee’s task, detailed in Box 1, was to review each evidence report and provide responses to nine specific questions. In summary, this report examines the quality of the evidence, analysis, and overall construction of each report; identifies existing gaps in report content; and provides suggestions for additional sources of expert input. This report builds on the 2008 Institute of Medicine (IOM) report Review of NASA’s Human Research Program Evidence Books: A Letter Report, which assessed the process for developing NASA’s evidence reports and provided an initial and brief review of NASA’s original evidence report.1

The committee approached its task by analyzing each evidence report’s overall quality, which included the report’s readability, its internal consistency, the source and breadth of the evidence it cited, its identification of existing knowledge and research gaps, the expertise of its authors, and, if applicable, the report’s response to recommendations from the 2008 IOM letter report previously described.

The committee again commends NASA for advising report authors to explicitly note the categories of evidence—ranging from expert opinion to data from controlled trials—that were relied on in these reports. This practice is now followed comprehensively in most, although not all, reports; the exceptions are noted in relevant sections below. As noted in pri- or letter reports (IOM, 2014, 2015; NASEM, 2016), substantial variability exists among individual evidence reports in the formatting, internal consistency, and completeness of the references, making it difficult to compare the evidence for related human health risks that is cited in the different reports. NASA is encouraged to select a preferred citation format for all evidence reports and to require all writing teams to use that format.

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1 The original evidence book was “a collection of evidence reports created from the information presented verbally and discussed within the NASA HRP [Human Research Program] in 2006” (NASA, 2013).

BOX 1Review of NASA’s Evidence Reports on Human Health Risks

Statement of Task

NASA has requested a study to provide an independent review of more than 30 evidence reports on human health risks for long-duration and exploration spaceflight. The evidence reports, which are publicly available, are categorized into five broad categories: (1) behavioral health and performance; (2) human health countermeasures (with a focus on bone metabolism and orthopedics, nutrition, immunology, and cardiac and pulmonary physiology); (3) radiation; (4) human factors issues; and (5) exploration medical capabilities. The reports are revised on an ongoing basis to incorporate new scientific information. In conducting this study, an ad hoc committee will build on the 2008 Institute of Medicine (IOM) report Review of NASA’s Human Research Program Evidence Books. That report provided an assessment of the process used for developing the evidence reports and provided an initial review of the evidence reports that had been completed at that time.

Each year, NASA staff will identify a set of evidence reports for committee review. Over the course of the study, all evidence reports will be reviewed. The committee will hold an annual scientific workshop to receive input on the evidence reports it is reviewing that year and an update on the recent literature. The committee will issue an annual letter report that addresses the following questions relevant to each evidence report:

Does the evidence report provide sufficient evidence, as well as sufficient risk context, that the risk is of concern for long-term space missions?

Does the evidence report provide evidence that the named gaps are the most critical presented?

Are there any additional gaps or aspects to existing gaps that are not addressed for this specific risk?

Does the evidence report address relevant interactions among risks?

Is input from additional disciplines needed?

Is the breadth of the cited literature sufficient?

What is the overall readability and quality?

Is the expertise of the authors sufficient to fully cover the scope of the given risk?

Has the evidence report addressed previous recommendations made by the IOM in the 2008 Letter Report?

In addition to analyzing the content of individual letter reports, the committee also gathered evidence from existing literature and relevant experts in the field. The committee held two conference call meetings and one in-person meeting, with the latter held in conjunction with a public workshop (see Appendix A). The committee invited individuals

This is the fifth, and final, in a series of letter reports that provide an independent review of the more than 30 evidence reports that NASA has compiled on human health risks for long-duration and exploration spaceflights. This letter report reviews five evidence reports and examines the quality of the evidence, analysis, and overall construction of each report; identifies existing gaps in report content; and provides suggestions for additional sources of expert input.

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